Traditionally, since the tray made from resin is light weight and rigid so it is used to store and transport heavy load such as shafts for vehicles, vehicle engine, finished goods and luggage etc. Resin tray is molded by using mold and it is necessary to prepare the mold for forming storage recess suitable for internal and external structure and size of stored goods. The block mold intended for general-purpose mold is disclosed in patent document 1. More specifically patent document 1 discloses that the mold is composed of a fixed mold and a movable mold for the palette made of the resin which is one side use type for molding lower half body that has the opening that penetrates vertically. By assuming either of molds as base mold, mold piece inserted for rib formation in mold is installed and some light weight type ribs and lot of high strength type ribs are molded by exchanging the inserted mold piece with changed thickness and number of ribs. However, the following technical points are considered according to such a general-purpose mold. That is, if there are many mold parts, the molding work efficiency is low, and the management cost increases. Especially, when the storage goods are elongated structure shaft of the circular section, a ditch is installed in the outline of the storage goods in the bottom so that rolling, breakdown does not cause any damage in the storage area where the storage goods are formed in the bottom of the tray. It is necessary to set and position the storage goods in this ditch. In this case, it does not fit if the block mold is prepared according to the outline of entire mold and if number of mold increases.
In addition, when minor change is done with the product that is to be stored, in every case block mold for base mold is rebuilt and considerable time is required to prepare the mold as arrangement for base mold is changed, and it becomes difficult to do an efficient molding. Thus, Flexible efficient mold preparation is demanded by the industry when goods to be stored are slightly changed.
The resin material in the molten state that should be molded between a pair of split molds (oppositely arranged) is arranged. Internally confined space is formed by clamping a pair of split mold. The blow pressure is put in the confined space. The technology that molds by pressing the resin material against the cavity is indicated. Especially, a detachable inserted piece is prepared for the cavity of the mold. The point to select the inserted piece according to the molded piece is indicated in patent document However, a mark is carved on the surface of the product and externals, and size of entire molded piece is not changed.